I just applied your patch and launched compilation. And it's currently compilating (surely I will have problems with SDL, but not with ARM GCC). The rockbox initialization script installs ARM GCC, and configures it automatically. So I just applied your patch, and ran "../tools/configure && make". See http://www.rockbox.org/wiki/LinuxSimpleGuideToCompiling and in particular the part about "./rockboxdev.sh". For the SDL, I think it won't be the same. But rockboxdev.sh it worth reading.